Multi-layered LiNbO3 films prepared by a polymeric precursor method

The polymeric precursor method was used to prepare multi-layered LiNbO3 fil ms. The overall process consists of preparing a coating solution from the P echini process and the deposited film is subsequently heat-treated. Two-lay ered films were prepared by this process, onto (0001) sapphire substrates. Two different routes were investigated for the heat-treatment. The "amorpho us route" consisted of performing, after each deposition, a pre-treatment a t low temperature to eliminate the organic material. In this case, the crys tallization heat-treatment was performed only after the two layers had been deposited. On the other hand, a process "layer-after-layer crystallization " was used. Both routes led to (0001) LiNbO3 oriented films. However, only the film prepared by the "layer-after-layer crystallization" presented an e pitaxial growth and a crack-free morphology. Moreover, the "layer-after-lay er crystallization" process led to a film exhibiting the best optical prope rties. (C) 2001 Elsevier Science Ltd. All rights reserved.